Gauge bar for grinding machines



J. BATH GAUGE an: FOR eanmma MACHINES Oct. 13, 1925 Filed Oct. 7 1924 Patented 0a. 13, 1925;

UNITED STATES,

PATENT OFFICE.

JOHN BATH, OF WORCESTER. MASSACHUSETTS.

GAUGE BAR FOR GRINDING MACHINES.-

Application filed October 7, 1924. Serial No 742,233.

thread chasers and other similar articles by a process of grinding a series of parallel grooves therein.

I It is the object of my invention to provide a'construction by which a full set of thread chasers may be ground at a single operation. To the attainment, of this object, I have provided a gauge bar of an improved type which will locate each one of a set of thread chasers so that the thread grooves will be accurately positioned thereon, with correct allowance for the angular relation of thedifit'erent thread chasers when in use.

My invention further relates to arrangements of parts and details of construction which will be hereinafter described and more particularly pointed out in the appended claims. A preferred form of in vention is shown in the drawing in which, Fig. 1 is a plan view of portions of a grinding machine having my. invention applied thereto:

Fig. 2 is'aplan View of, my improved gauge bar:

Fig. 3 is an end elevation of the parts shown in Fig. 1:

Fig. 4 is an. end elevation of a thread cutting die, and

Fig. 5 is aside elevation'thereof.

Referring to the drawings I have indicated a portion 10 of a work support or table forming art of a thread grinding machine. A suitable chuck 11 is mounted on the table 10 and is secured thereto in any convenient manner asby clamping bolts 12.

The chuck shown in the drawings is of the magnetic type but any other convenient form of chuck may be substituted. An angle plate or guide 13 is secured to the side of the chuck 11 and projects over the magnetized face of the chuck. 1

My invention relates particularly to the provision of an improved gauge .bar .14 for correctly positioning aseries of "thread chasers A, B, C, and 1).. The gaugebar 14 has a projecting portion 15 which is under cut or recessed so that the thread chasers may be secured firmly agalnst the portion 15 and so that dirt will not interfere withsuch positioning.

When the thread chasers are in use, they are mounted in a die head 16 as indicated 1n Fig.4, the chasers being placed in a series of equal-spaced angular positions. As the chasers are commonly positioned in the same radial plane, it is evident that the thread grooves on the difl'erent chasers must be differently located to compensate for the different angular positions of the chasers.

' In order to' produce a set of thread chasers having the threads correctly located for use in a thread die, I have provided .the gauge bar 14, with a series of gauge surfaces 18. These gauge surfaces are disposed in a longitudinal series along the edge of the gauge bar and are parallel, but each sur face is spaced transversely from its adjacent surfaces by an amount equal to a proportionate fraction of the pitch of the thread to be cut by the thread die.

If fourthread chasers are usedin a set, each surface 18 will be olf-set by an amount tivepositions of the different surfaces 18 are clearly indicated by the dotted construction equal to one-fourth of the pitch. The'relaand a series of chaser blanks are then placed against the gauge surfaces 18. Electric cur rent is then turned on to excite the magnets and hold the gauge bar and blanks firmly against the chuck.

The grinding wheel W (Fig. '3) is then reciprocated over the work, cutting the series of thread grooves as indicated in the drawings. When the finished thread chasas indicated in Figs. 4 and 5, it will be found that each. thread chaser is correctly ers are thereafter assembled in a die head,-'

located to co-operate with the other thread chasers and cut a perfect thread.

By this construction all of the dies in a set may be ground at a single operation and it is not necessary to separately position and grind each'mdividual chaser. My construction therefore results in a. considerable saving of time. and labor as well as in increased accuracy of the roduct.

Having thus describe my invention, I do not Wish to'be limited to thevdetails herein disclosed otherwise than as set forth in. the claims but what I claim is 1. In a thread grinding machine, a gauge bar for thread chasers having a plurality of parallel gauge surfaces spaced transversely from each other by equal fractions of the pitch of the thread tobe ground.

2. In a thread grinding machine, a gauge bar for thread chasers having a plurality of parallel gauge surfaces disposed in a longitudinal series along one edge of said bar and spaced transversely from each-other by equal fractions of the pitch of the thread to be ground.

3. In a thread grinding machine, a Work table and a grinding wheel, one travelling relatively to-the other, and a series of sto S\ on said table spaced transversely to t e direction of relative travel of said table and wheel, and each stop being ofiset from its adjacent stops by a selected fraction of the pitch of the thread to be ground.

In testimony whereof I have hereunto aflixed m signature.

y JOHN BATH. 

